Abstract: Cleaning tablet for the automatic cleaning of dentures in an aqueous solution, with a content of sodium hydrogen carbonate and/or sodium carbonate or carbonates, citric acid or citrate or citrates, sodium perborate, potassium monopersulphate, surfactants and foam forming agents, binders, lubricants and disintegrants, antimicrobial agents, carriers, flavoring/aromatizing substances, at least one perborate/peroxide activator and at least one phosphorus compound, characterized in that the activator content is between 0.5 and 3.0% by weight of the total composition of the cleaning tablet, is the phosphorus compound is includes at least one hydrolysis-stable organic phosphonic acid and/or a salt thereof that acts as a stabilizing agent and having a content between 0.5 and 3.0% by weight of the total composition of the cleaning tablet and that the total composition of the cleaning tablet is free from inorganic phosphates/polyphosphates and organic sequestrants based on aminocarboxylic acids and hydrophobic binders.